Composite sheet materials often include a glass layer at at least either surface to achieve light weight and surface protection from scratching. One known type of such composite sheet materials is a laminate having a glass layer formed by bonding sheet glass to the front surface of a pre-molded resin sheet. Another type is a laminate having glass layers which are formed by bonding sheet glass to the front and rear surfaces of a pre-molded resin sheet respectively such that the resin sheet is sandwiched between the glass layers.
These types of composite sheet materials, however, reveal the drawback that since sheet glass is bonded to a pre-molded resin sheet, gaps are created between the resin sheet and the sheet glass if the surface of the resin sheet is not flat because of warp and shrinkage and these gaps result in bonding defects.
The invention is directed to overcoming this problem and one of the objects of the invention is therefore to provide a composite sheet material and its producing method, the material having at least a glass layer constituting either one of its opposed surfaces for the purpose of surface protection from scratching. This composite sheet material can be easily produced without causing bonding defects and is free from stress-strain.